CD8A and neoplasm: By interrupting the programmed death protein 1 (PD-1)/programmed cell death 1–ligand 1 (PD-L1) regulatory axis, cytotoxic T lymphocyte antigen-4 (CTLA-4), or others, immune checkpoint inhibitors (ICIs) can initiate T cell activation and expansion, increasing the quantity of activated tumor-specific CD8+ T cells.